This invention relates to a heating element for an air flow heater.
Air flow heaters are used in many situations for example as hair dryers, space heaters, interior car warmers. In many cases the heating element which is located in the air stream generated by a fan of the heating device comprises a coiled electrical resistance heating wire which is supported by non conductive support sheets often of ceramic or mica.
Various different designs have been proposed but the most common design comprises three vertical baffles arranged generally parallel to the air flow with two of the baffles arranged at ends of the air flow and a central one of the baffle arranged between the two end baffles. The helical coils are then strung across between the baffles and supported thereby so that the axis of the coils is transverse to the air flow. This arrangement has been manufactured widely and can be manufactured relatively cheaply particularly where labour costs are relatively low. However this arrangement has a number of disadvantages. Firstly the amount of heating wire that can be supported across the air flow is relatively low thus leading to a relatively low density of wire so that the heat of the wire or the watts per unit length of the wire must be relatively high. This leads to a high temperature of the wire which reduces wire life and increases radiant heat from the wire which can cause damage to the surrounding plastics housing. The second disadvantage is that the wire must be supported by a central baffle between the two end baffles which interferes with the air flow across the wire element thus generating areas of reduced air flow which cause hot spots in the wire again reducing wire life and increasing the danger of damage from radiant heat.